Australian Seismological Reference Model

The Australian Seismological Reference Model (AuSREM) is designed to bring together existing information on the Australian continent of many types, and provide a synthesis in the form of a 3-D model that can form the basis for future refinement from more detailed studies.

P wavespeed distribution for the AuSREM crustal model at: 5, 15, 25 and 35 km depth. Refraction constraints are indicated by squares and receiver functions information by diamonds.

The AuSREM model is grid based with a 0.5 degree sampling in latitude and longitude and is designed to be fully interpolable, so that properties can be extracted at any point.

The crustal component makes use of prior compilations of sediment thicknesses, with cross checks against recent reflection profiling, and provides P and S wavespeed distributions through the crust. The primary information for P wavespeed comes from refraction profiles, for S wavespeed from receiver function studies, and the results of ambient noise tomography are used to link the point observations into national coverage.
AuSREM is able to build on a new map of depth to Moho, which has been created using all available information including Moho picks from over 10,000 km of full crustal profiling across the continent (Kennett et al., 2011).

Slices through the AuSREM mantle model for SV wavespeed at: 100 km, 150 km, 200 km and 250 km depth.

In the upper mantle the primary source of information comes from seismic surface wave tomography and a representative model has been developed to capture the features of a range of studies. Body wave studies and regional tomography provide useful constraints on the relation between P and S wavespeeds. The mantle model extends beyond the continent and so covers a larger area than for the crust. Below 350 km and in the surrounding area AuSREM is linked to the S40RTS model (Ritsema et al., 2011).

The full AuSREM model provides a representation of 3-D structure beneath Australia and its environs that can be used for many purposes, including the delineation of major structural features in the crust and mantle. Both crustal and mantle components should be useful in gravity modelling and in studies of dynamic topography. AuSREM provides crustal corrections for surface wave tomography and delay time tomography on a finer scale.

Tools are under active development for location of earthquakes in the full 3-D model, and for earthquake source characterisation.

For more information read the AuSREM Overview.